Almost since their invention, lasers have been successfully utilized for delicate surgery, such as ophthalmic surgery. Delicate surgery, by its nature, requires precise placement of the cut, or burn of the laser, in order to avoid irreparable damage to the tissue under treatment. Lasers aim only a small beam of light at the tissue, but the accuracy of the aim depends on the surgeon's skill and the lack of movement on the part of the area to be treated. Various apparatus and techniques for laser surgery exist and are described in the patent literature:
U.S. Pat. No. 4,597,649 describes information display apparatus for ophthalmic slit lamps wherein an LED display is provided between the collimator and the eyepiece and is suitable for display of laser operational data in addition to positional data.
U.S. Pat. No. 4,503,854 describes ceiling mounted laser surgery apparatus having a motorized micromanipulator delivery system which is compatible with a microprocessor for automated surgery. A built in digital television system is provided for demonstration, recording or for use as a robotic eye in association with a computer used to control the laser surgery.
U.S. Pat. No. 4,638,800 describes a laser beam surgical system including a cannula which carries a white light conduit and a carbon dioxide laser light conduit.
U.S. Pat. No. 4,686,992 describes an ophthalmic beam director having an automatic centering device.
U.S. Pat. No. 4,722,056 describes reference display systems for superimposing a tomographic image onto the focal plane of an operating microscope.
U.S. Pat. Nos. 4,538,608; 4,669,466; 4,665,913; 4,718,418 and 4,729,372 all to L'Esperance, Jr. all relate to laser ophthalmological surgery.
U.S. Pat. No. 4,672,963 describes an apparatus and method for computer controlled laser surgery. The computer system provides a display of tissue, acquired with ultrasonic means, within the patient. The attending physician provides input, describing tissue to be irradiated, with a light pen into the computer. The computer system then controls both the duration and intensity of the laser burst to accomplish tissue destruction. The system is not fully automated and depends on input from the attending physician, during the surgical operation, to define the areas to be irradiated and to position the laser guide. In addition, the system depends on ultrasonic means for its image acquisition.
B. Jean, et al, in a paper, "Eye Tracking for Image Stabilization," in Lasers in Ophthalmology, discuss a system for real-time tracking of eye movements and image stabilization. The system effectively tracks eye structures on the retina and in the anterior eye; however, it is not operative to perform surgery. The system described in the paper does not incorporate the processes of firing a laser beam at a target point, checking that the burn was properly placed and moving to the next target point which are necessary for an automatic laser surgical system.